1. Field of the Invention
The present invention relates in general to bevelling machines and in particular to a new and useful portable device having an adjustable bevelling head for bevelling tubes.
2. Description of the Related Art
In the welding field, the current method for machining weld preps on the ends of tubes is to use a tube beveller which is a small, air powered tool having high speed steel cutters. These known tube bevellers are clamped to tubes through the use of an internal mandrel. These machines are typically light duty machines utilizing low power because they are intended for only limited production use, particularly, during the refurbishment of boilers.
In many instances, the refurbishing of a boiler requires the joining of tubes through welding. In order to ensure the quality of the field welded joints used, the weld preps, i.e. the tube bevels, must be machined with uniform, consistent diameters. The known bevellers use cutters which are normally adjusted with set screws. The set screws are difficult to adjust accurately and tend to drift easily from the desired setting. In addition, the high speed steel cutters must be reground frequently. Each regrinding operation requires an additional setup.
Generally, during a tube bevelling operation, the tube bevellers are clamped to the tube with an internal mandrel which passes through the center of the bevel machine. Because of the location of the mandrel, the size of the mandrels is limited. Because of the limited size of the mandrel, breakage of the mandrel is a common occurrence.
In an effort to reduce manufacturing time during a tube bevelling operation, an internal bevel is produced simultaneously with an outside bevel for the tube. Consequently, the internal mandrel, described above, greatly restricts the use of the internal cutters of known bevellers which necessitates an additional hand reaming operation. This additional manual step requires significant labor and greatly reduces the accuracy and consistency of the bevel.